


Dawn, Insert Last Name Here

by Jedi Buttercup (jedibuttercup)



Category: Buffy the Vampire Slayer, Iron Man (Movies)
Genre: Crossover, Gen, Gift Fic, Paternity Tests, Post-Chosen, Pre-Movie(s), Wordcount: 5.000-10.000
Language: English
Status: Completed
Published: 2015-08-03
Updated: 2016-10-27
Packaged: 2018-04-12 19:39:11
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 5,100
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4492167
Author URL: https://archiveofourown.org/users/jedibuttercup/pseuds/Jedi%20Buttercup
Summary: <blockquote class="userstuff">
              <p>The discovery that Dawn Summers was maybe not actually a Summers began like so many other dramatic changes in her life: with a disappointment.</p>
            </blockquote>





	1. Dawn, Insert Last Name Here

**Author's Note:**

  * For [Jiltanith](https://archiveofourown.org/users/Jiltanith/gifts).



> Chapter 1 for the prompt: B:tVS/Iron Man (MCU). There's a reason Dawn Summers is so smart; she gets it from the guy who turns out to be her real genetic father, [SPOILER]; Chapter 2 for the prompt: "the next part of Dawn-is-a-[SPOILER]."

The discovery that Dawn Summers was maybe not actually a Summers began like so many other dramatic changes in her life: with a disappointment. This particular one came in the form of a letter, delivered casually in a batch to the Hyperion in Los Angeles one sunny Saturday.

Buffy had decided to park the last bus out of Sunnydale at Angel's place after the collapse of the town; her ex's hotel had plenty of empty rooms, and it had given them time to let the wounded heal, start sending out teams to recruit or inform the new Slayers popping up everywhere, and make plans for a new headquarters in Cleveland. With the Watchers' Council nearly extinct, and the Hellmouth there growing more active, the Scoobies all figured they'd end up there eventually... but it was summertime, the slow season for vampires and most other demons, and _all_ of them needed a little break from the life-and-death struggle of Slayage.

Dawn had taken the opportunity to send a letter to her father, in a last-ditch attempt at reclaiming at least one thing she and her sister had lost. She hadn't really expected anything to come of it, not after so many years of silence. But she'd thought someone at least ought to tell him that his daughters weren't dead.

Three weeks later, her morning flip through the mail turned up an envelope addressed "To: Dawn", a little larger than a standard number ten but smaller than a catalog; the postage was international, and it was postmarked from the Canary Islands. Her breath caught as she snatched the envelope from the pile, and she ran up to her room before anyone else could see it and ask her what it was.

Then she took a cross-legged seat on her bed, cracked the flap with a fingernail, and slid out the sheets of paper inside.

* * *

Two hours later, Dawn walked slowly back down the main staircase, face reddened more with fury than tears as she hunted down her sister.

"Buffy, did you know about this?" she demanded, striding into the meeting room Buffy had appropriated as an office on the floor above the lobby.

"Know about what?" Buffy asked absently. She didn't even look up; she was all absorbed in something she was going over with Willow, papers and laptop spread all over the room's big oval table.

" _This_ ," Dawn hissed, casting the pages still clutched in her hand down onto the table in front of Buffy.

Buffy frowned at the slightly crumpled sheets of paper, reaching out to smooth a hand over the worst of the creases. "Dawn, you're going to have to give me a little more to go on. Is this...." Her voice trailed off as she traced over the logo on the top sheet, then the name immediately under the date marked on the letter. "Where did you get this? I thought all Mom's correspondence went down with the Hellmouth."

"It wasn't Mom's copy," Dawn replied, ignoring the pained note in her sister's voice as she scowled at the letter. "It was _Dad's_. At least, the guy I _assumed_ was my dad. I don't know why, I mean, it's dumb, right? We always figured the monks made me sometime that summer before Glory showed up, and Mom had been divorced for _years_ by then."

Buffy looked back down at the letter, then back up at Dawn, eyes widening. Then she hastily shuffled the child support reminder aside to look at the pages underneath. The next two were the ones Dawn had spent most of those two hours staring at, alternately wiping her eyes and cursing the entire Order of Dagon. They contained three columns of numbers each, under the headings: MOTHER, CHILD, ALLEGED FATHER.

One of the reports showed paternity at 99.9996%. The other... did not.

Willow took the pages from Buffy's frozen fingers. "He did a DNA test on you?"

"Both of us," Buffy replied, stunned, reaching for the fourth sheet of paper-- the one actually signed Hank Summers.

Dawn averted her eyes; it had hurt enough when _she'd_ read it, she didn't need to see Buffy's reaction to what their-- _her_ \-- father had had to say for himself.

"I mean-- I'd wondered, given everything they said about you being made from Buffy," Willow continued. "But I figured if that was the case, you'd still be Joyce's, just one step removed. So why even ask?" She threw a side-eyed glance at Buffy. "It wouldn't help anybody to know, and it might make things worse."

Dawn had wondered the same thing once or twice, and come to the same conclusion: that it was better not to know. It wouldn't have made Mom any less her Mom, or Buffy any less her sister, whatever her genes said. And if somebody told the wrong person about it, then what? It wasn't like they could explain it with the truth; no one wanted to risk some new bad guy figuring out a different use for Glorificus' Key.

Maybe she should have asked, though. Maybe this would have come as a little less of a surprise.

"Well, it has," she said, grimly.

"He thought it was some kind of scam," Buffy said thickly, dropping the letter as she tuned back into the conversation. "Apparently for years, since the first time Mom contacted him for child support. That she must've had a kid with some other guy after the divorce and tried to pin it on him, and there was just some confusion going on about your age."

"Because he doesn't remember me," Dawn said tightly, gritting her teeth again. " _Did you know_?"

Buffy shook her head and met Dawn's gaze, stricken. "No. God, no. How could you think that?"

"Like you haven't been known to keep secrets from me supposedly for my own good before?"

"Hey, hey," Willow interjected. "This isn't Buffy's fault, Dawn. _Or_ yours. It's the stupid spell the monks used; wholesale reality alteration is really expensive, magically speaking, and they didn't have much time. They must not have had enough juice to catch him in Spain."

"Whatever. Forget the spell," Dawn waved that off. It wasn't like she had all that many great memories of Hank anyway; she barely remembered a time in her childhood when her parents weren't fighting. It was the secret factor that was pissing her off; she'd had so much of her identity ripped away from her already one way or another, one more piece was just _beyond_ enough. "What I want to know is, if _he_ isn't my father, and I'm not some magical mix of Buffy and Riley or something... then who the hell _is_ my father?"

Buffy wrinkled her nose, then thought a little more about the question. "That's... a good question, actually. Mom wasn't the one who screwed around; there _isn't_ anyone else she could have slept with in 1985."

"That you know of," Willow said, then hastily continued at Buffy's disgruntled look. "But you're probably right. I mean, we figured the monks made Dawn in the summer of 2000, right? By the time Dracula showed up, at the latest. So if they picked from your mom's current life when they decided to give you a sister...."

She trailed off there, her expression turning speculative, and Dawn gaped at her, horrified by the implication. "You can't be serious. I mean, _Dracula?_ Why would they even, why would you think...?"

"Mom _did_ invite him in for coffee...." Buffy added with a shudder, looking equally dismayed.

"God, Spike would _die_ ," Dawn cringed, then turned back to Willow. " _Please_ tell me it can't be true."

"If you'd been born the normal way? No; not without major prophetic intervention. But we're talking mystical creation, here; that might trump the whole dead sperm thing." Willow bit her lip, then stepped away to open the doors of a cabinet flanked by heavy bookshelves filling with Giles' salvaged books. She checked the labels on several of the small containers on the shelves inside, tracing her fingers over spidery script and raised block letters, and nodded to herself. "I _can_ do a spell to search for your bio-dad, though. A cross between a location spell and a parentage verification should work; the latter's usually done in person, but I should be able to link them together with a little creative Latin. Assuming, you know, that he's still alive."

"I'll get a map," Dawn said, and hurried to one of the other cabinets. 

Maybe finding out the truth wouldn't change things any more than it would have if Buffy had turned out to be her bio-mom. But either way, now that she knew there was something to know-- Dawn had to know it.

* * *

Two days later, Dawn parked in front of a glass and white stone layer cake of a house, all swooping lines and reflective windows at the end of a winding, tree-lined drive. 

Willow's first attempt at the spell, cast over a Mercator projection map, had lit up with only one glowing dot: a softly pulsing blip over the Los Angeles area. She'd thought it had failed at first; that it was only showing Dawn, or maybe Buffy, not her father.

Just to be sure, though, she'd tried again with a California state map-- and _that_ one had lit up just a little too far west to be showing any Summers. A close-up area map had clarified it even further, resolving the glowing dot a little over thirty miles west of the Hyperion: out at Point Dume.

10880 Malibu Point, to be precise. The address of record for exactly one, unbelievable human being.

"How the hell did Mom ever meet him?" she murmured under her breath, wiping sweaty palms against her jeans. Then she shook her head at herself and walked up to the intercom button she could see by the door, pressing it with her thumb.

She'd thought about calling first, but she'd have had to call one of the public Stark Industries numbers, and she hadn't been able to see that going anywhere fast. If she'd been lucky enough to get a live person, she'd probably have ended up getting the cold shoulder from his PA or his lawyers... and if any of them _had_ decided to take her seriously, they'd have thought she was just after his money.

If only it was that simple. Heck, even _Dawn_ didn't know why she was there, without backup or proof or anything; she had a stomach full of bees, a complete inability to sit still, and a worried certainty that _he_ wasn't going to believe it, either. Or worse yet, that _she_ shouldn't believe it; that the spell had done nothing but get her hopes up.

"Dawn Summers, to see Mr. Stark," she said, with only a little shakiness in her voice.

"Mr. Stark is not available," a cool British voice replied, almost immediately. "If you have legitimate business with Mr. Stark, please contact the Stark Industries offices during regular hours."

"How do you know I don't have an appointment?" she frowned, taken off guard. That had been a little abrupt.

"There is no Dawn Summers on Mr. Stark's schedule, today or any other day," the Brit continued.

"How about _Joyce_ Summers?" she tried, pressing the button again. If this guy kept his schedule, he should be able to find that one, if there even was anything to the whole idea. Mom would have had to be associated with Tony Stark _somehow_ for the monks to pick him, right? "About three years ago? She owned an art gallery in Sunnydale."

There was another pause, then someone else replied. "Owned? Past tense?"

"Mr. Stark?" Dawn blinked at the change of voice.

"Why would the-- what, daughter?-- of a woman I once bought art from show up on my doorstep all this time later? Not because of any of my purchases, I trust? Not that I checked; but I assume my assistant would have told me if any of the authentication paperwork turned out not to be genuine."

So, she'd been right; they _had_ met. Wow. Then why hadn't Mom said anything?

She thought about that for a moment, then swallowed as she realized what the logical answer had to be. Because there had to be more to it than that for it to be _him_ , and not any other male customer Mom had met that year. And there was only one good reason Dawn could think of that Joyce Summers wouldn't have wanted to tell her teenage daughters about.

"Not because of your purchases, no," she finally answered, wincing. God, it was _true_.

There was a long pause on the other end of the intercom; then a sharp command. "Wait there."

Dawn wrung her fingers together, half-wishing she _had_ asked someone else to come with her. But she hadn't wanted any witnesses, just in case of... whatever; and this was certainly _whatever_. She would've thought Mr. Stark would start a security check, ask for a way to contact her or set up an appointment or something; but she guessed he was as impatient to know already as she'd been.

Which... well, did kind of make sense, if any of this even did. She laughed nervously, then turned as the door abruptly opened, revealing a dark-haired, dark-eyed man with a neat goatee and _much_ messier clothes than anything she'd seen in the tabloids. He looked... kind of like a normal person, actually, wearing a band tee shirt with grease on his knuckles. But there was something in the intentness of his gaze that made her freeze like a deer in the headlights, similar though not identical to Buffy in focused Slayer mode. 

"Jarvis just brought up the obituary," he said, abruptly, studying her. "February, 2001. Survived by two daughters, neither of whom was an infant. And I've had a medical check since then. What possible reason could you have left to contact me _other_ than the art? Which by the way, I'm not even sure I still have. My assistant curates my artwork for me."

Dawn stared at that brick wall of an expression, taken aback. She now knew more about her mother's sex life than she'd ever wanted to; had he seriously just implied this might be about an STD? Why hadn't she thought this through? She _so_ hadn't expected that, and she really should have.

She should have thought more about what to say next, too. How was she supposed to drop it on him? 'Thanks to a group of monks and a ball of magic powerful enough to destroy the universe, you might have retroactively knocked up a recent one night stand, _seventeen years ago_?'

She kind of doubted the monks had altered Tony Stark's memories any more than they had Hank Summers', beyond the obvious necessary meeting with her mother in 2000. If they'd added in an encounter in 1985, Mom would have been twenty-seven, and according to the articles she'd read, Tony Stark would have been a fifteen year old MIT student. If she'd remembered anything like that, she'd have reacted a _lot_ differently when the subject of Dad's cheating with his secretary got brought up. Just, _no_.

"Uh, sorry, I didn't mean to bother you," she blurted, courage failing. "I'm, uh. Have a nice day?"

Her hand rose almost without prompting to give a little finger-waggle of a wave, and she cringed at the complete fail of the moment.

At least she knew, right? At least she'd finally met her dad in person. That was more than she'd been able to say about Hank, even before the letter. She took a deep breath, shaking her head at herself, and turned to slink ignominiously away.

Before she could make her escape, though, Stark unexpectedly spoke again. "Wait. Dawn. You're, what, sixteen, seventeen, eighteen?"

"Seventeen in a couple months," she said, pausing in surprise to look at him. "Why?"

"Junior in high school, or accelerated coursework?"

Dawn snorted. "Junior, if I'm lucky and they don't count the loss of all my school records in Sunnydale against me. Maybe Senior if I'm luckier and Buffy lets me take a placement test instead."

"Hm. Bored by school, I'm guessing?"

"Why do you care?" she frowned back. "I just admitted I've been wasting your time."

"I think that's up to me to decide. Are you one of Dad's?" he interrupted, studying her again. "Hair color from your mother, obviously, but something about the eye shape, the chin; even your smirk. It's distracting. He was a little creaky in the knees by the mid-80's, but not too old to screw around, and I've wondered how many stray siblings I never met. If your mother was here to collect a father-and-son set, _please_ don't say so; that's a little kinky even for me. But I'm thinking _you_ came for a DNA test before you thought better of it."

That would make the perfect excuse, if she still wanted one. But if he did run a test, he'd find out the rest pretty quickly... and then she'd be right back at square impossible.

"What difference would it make if I was? It was stupid to come here."

"No Stark ever born backed down," he waved that away, eyes narrowed, "and I'm betting you won't be the first to buck the trend. Unless you really _are_ just yanking my chain, here...?"

"That's a false dichotomy," she protested, desperately. "What if I just don't want to be a Stark?"

"And that's a rhetorical question; you're here, aren't you?" he dismissed that with a raised eyebrow. "And now that you've got me curious, you're not getting away that easily."

She stared at him; he stared back.

Then she sighed. Buffy was gonna kill her. But the Scoobies did the impossible six times before breakfast, right? "You've got me there."

He smiled at that; a white flash of teeth, there and gone as quickly as one of her sister's rare actual smiles.

"Then let's find out."


	2. Teenage Trojan Horse of Chaos

JARVIS being JARVIS, there was no question of farming the paternity test necessitated by the presence of the nervous teenager on Tony Stark's doorstep off to an outside lab for analysis. J could do the job in a snap; and he even had the equipment on hand to run it.

Tony being Tony, he'd faced enough spurious paternity challenges over the years to make damn sure he had his own PCR machine in the odd event that he actually remembered having sex in the applicable time frame with the woman claiming he'd knocked her up. Contrary to popular report-- not to mention certain old sticks in the mud who'd known him since he was a kid in footie pajamas and were always after him about his media image-- Tony _never_ got drunk enough to actually fuck with his memory. The brain in his skull was the only one he had, and nothing good ever came of making himself that vulnerable. And even if by some happenstance he _had_ managed to forget, there had always been Jarvis, and then JARVIS, to remind him.

Not a single one of those paternity tests had ever turned up positive. He had a gut feeling, though, that this one would be different. He didn't exactly have a sample of Howard Stark's DNA on hand to test Miss Summers' against, and had little to no desire to go digging through any boxes of his father's things that might be kicking around the basement to find one, but he figured a half-sibling's sample should be good enough for conclusive results. It would match in the neighborhood of 25% rather than 50%, as any child who'd ever drawn a Mendel pea plant chart would have been able to figure out before she ever thought about walking up to his door, but that would still be more than enough to be sure.

"Last chance to take the blue pill and walk away," he said, gesturing toward the capped collection swab he'd dropped on the coffee table. Normally he'd assume anyone behaving that nervously was worried about getting caught in a lie, particularly in combination with the big blue eyes of appeal currently being aimed in his direction, but from the cues she'd dropped so far, she seemed more worried about his reaction to being proved _right_ than being proved _wrong_.

_Everything_ about Dawn Summers' appearance there, even the fact of her existence, was all backwards. It was the most interesting puzzle he'd been presented with in quite some time, if he didn't count the Jericho project-- which he didn't, because all of the technology for the missile had already been invented, it was just down to linking it all together to create the desired effects.

She reached out to pick up the swab, then clenched it tight in one shaky fist, swallowing hard.

"What if... what if it doesn't show I'm your sister?" she asked nervously, tucking a lock of her shiny waterfall of brown hair back behind one ear. She was still staring at him as though the secrets of unified field theory were written in the shape of his goatee; and as though that thought unnerved her as much as it energized her.

Tony snorted. Did she really think something that simple would trip him up? "Of course it won't; it'll show you're my _half_ sister. You wouldn't be here, clutching that swab in a death grip, if the test wouldn't show _anything_ ; you'd already be out the door, fuming that I'd called your bluff and calling whoever convinced you to come here. And as we already established, you're too old to be my daughter. Anything further out, and it wouldn't be worth all this trouble to establish the relation; ergo, half sister. You know, I _am_ curious what's got you so wound, but not enough to wait around while you satisfy your sense of teenage drama. So do the thing," he gestured with one hand as though working a toothbrush, "then follow along to the lab, and we'll figure out how much of our dear dead daddy's estate you're owed."

Dawn gaped at that, mouth falling open as though she hadn't even _thought_ about how much Tony might pay her to keep her quiet, even if Howard's will turned out not to have an 'other heirs of the body' clause. Which it had; one of the reasons Tony wasn't terribly surprised that one had finally crawled out of the woodwork. "What? You think I came here for _money_?"

"Wow." He blinked, working a fingertip into one ear as the shrill register of her voice climbed beyond tolerable range, then turned and strode over to the sideboard where the good scotch hid. "Was that high C? Sounds like you definitely inherited the Stark showmanship gene; full marks. How much practice does it take to master that degree of innocent indignation?"

Her jaw was set and her face flushed red by the time he turned back to her; much more expected, but no less intriguing, given the genuine wobble of hurt Tony could see at the corner of her mouth and in the fists now clenched at her sides. The verbal jab had been as much a test as a genuine question; people who ingratiated themselves into his life who weren't there for the money or power he could give them were so vanishingly rare that he could count them on one hand. He'd realized long before he was legally of age to drink that you could find as much veritas in indignation as any bottle of vino, and he could definitely use a little more insight here.

"Look, I've had a pretty terrible month already," she replied, her tone clipped with anger. "My whole town fell into a sinkhole, a bunch of my friends were killed by a religious nutcase, and the guy I _thought_ was my dad replied to my 'we're still alive' letter with a fucking _DNA test_ and a slur about Mom. I don't need this crap from you, too. I'm living in my sister's ex-boyfriend's hotel in LA, and _he_ works for Wolfram and Hart; if I was after your money, don't you think I'd have gone through him first?

"I just... you know what? Forget it. I can see this was a mistake." She tossed the collection swab down on the table and turned toward the door.

Strangely enough, the mention of Wolfram and Hart weighed _for_ her truthfulness, rather than against it, more because of than despite all Tony had heard from his own lawyers about that extremely shady firm. She was right; if she was out to gouge him, going through _them_ first would make more sense. But the gist of her statement seemed to imply that she thought the test would show that she was _his_ daughter, rather than Howard's... and barring time travel or sneaky mad scientist intervention, that just wasn't possible. 

Contrary to popular belief, Tony hadn't actually lost his virginity until he was 17; his genius had worked against him in school rather than for him, given how much younger and smarter he'd been than everyone else. Even at MIT, though at least there he'd had a friend in Rhodey to offset the worst of the bullying. He'd more than made up for it since, but that didn't change the facts.

"So which is it, then?" he blurted out without bothering to clarify first; another half-test, half-question. "Assuming you're not lying. You strike me as the responsible type; don't you think it might be relevant to my interests? At least to know whether I should be preparing for breakthroughs in temporal physics, or some kind of slow-burn mad scientist ploy."

The questions froze her in her tracks, and she turned back toward him, face pale and blue eyes wide with shock. "What...? How did you...? I mean, why would you even ask....?"

No objection, no wondering what the hell he was asking about? Damn. "Now I _really_ need a drink," he muttered, tossing back the contents of his tumbler and pouring another few fingers of amber liquid.

Howard Stark was the one whose life had been full of demigods, monsters, and really questionable scientific advancements; Tony had been playing catchup since he was old enough to recognize the red, white and blue of Captain America's uniform. The arrival of a teenage Trojan horse of chaos was really making him wonder if he'd just been a little behind the curve in inheriting that larger-than-life heritage.

Dawn swallowed hard, staring at him, then tipped her chin up, nerving herself up for something. "It-- it's not time travel," she said, firmly. "That letter from Dad-- Hank-- he said had the test run because he had no idea I even _existed_ until Mom asked him for child support out of the blue, several years after the divorce. He thought it was a _joke_ ; even tested my sister, too, to prove it. But he's not the only one who doesn't remember me who should; it turns out, I don't have any paperwork outside of Sunnydale, not even a birth certificate. It's made getting a new driver's license kind of a nightmare.

"There's secrets involved that aren't mine. And stuff you're never gonna believe, not even if I _did_ have proof, which I don't, because the police in Sunnydale were mostly corrupt and all the town's records went down with the sinkhole anyway. But-- as far as we can tell, there isn't any physical evidence of me existing before three years ago. Except that everyone in Sunnydale, including me, _does_ remember me always being there. So call it magic, or mad science, or whatever makes you happy. But you're the only one I know for sure that Mom slept with after Hank. I didn't exactly come here meaning to tell you any of that, though. I just... I don't know, I guess I didn't think it through."

"Now, that _does_ sound like me," Tony snorted, taking another sip from his glass as he studied her expression.

He got the impression from the grim line of her mouth that she meant it about the secrets; fair enough, considering his reputation and the fact that they'd just met. There were a _lot_ of unanswered questions there, though, starting with what the hell someone would want with a kid of his anyway, enough to either somehow obtain his genes seventeen years ago and mix them with a random woman in Los Angeles, raise the kid for fourteen years, and then dump her randomly back with her maternal genetic contributor as an experiment-- extremely unlikely, unless said mother was in on it, and he hadn't got that kind of impression from Joyce-- or somehow quick grow her and _then_ mind control everyone to believe she'd always been a normal kid for some mysteriously nefarious reason.

Except that even Maya Hansen's experimental quick-growth therapy-- which he vaguely remembered being a little too explosive for actual application-- was aimed at quickly repairing adult tissue, not accelerating an entire life cycle. And mind control on the level either version of Dawn's story would require was heavily resource intensive, and rarely left no traces behind. 

Although... starting her off at fourteen was actually genius, if whoever had been behind her creation had wanted to observe her in the wild awhile. Old enough to mostly take care of herself, but young enough not to require all the various complex layers of adult identification: drivers licenses, bank accounts, SAT scores, voter registrations, and the like. It sounded like there _would_ have been proof at some point as well, if not for officious interference... and in the new computer-driven world, such things rarely disappeared entirely.

"And....?" she prompted him, crossing her arms over her chest.

He shrugged. "Well, as I said before our little side trip to the Twilight Zone-- now that you've got me even _more_ curious, you're still not getting away that easily. Verification first; we'll run that test, and set JARVIS on your little records problem. Then I'll have to contact Pepper and Obie to get the ball rolling on PR, though I think I'll let them make the same assumption I did. A sudden half-sister will play a lot kinder with the stock market than the otherwise obvious conclusion."

"Just like that?" Dawn's eyebrows went back up; she was still pale, but the sassiness was coming back.

Good kid. Whatever else she was, this possible daughter of his was the furthest thing from _boring_.

"Just like that," Tony replied, the corner of his mouth tugging up in a smirk.

**Author's Note:**

> 


End file.
